Oh, please oh please install the security updates from Microsoft and any other vendor whose software you run. I've just been talking with a bunch of users who are experiencing problems with a major website. Looks like if you have the latest updates from Microsoft, there's no problem, but of course, these people weren't updating their computers.
It's so easy. Visit http://updates.microsoft.com and click the Express button. Even better, if you see a choice that says something about using "Microsoft Update" choose that; this will update most of your Microsoft software including Windows and Office. Pick all of the automatic options to make it even easier.
It's a dangerous world out there with lots of bad people who want to break into your computer. We fix tons of security issues as well as reliability problems in these updates. It's definitely worth keeping up-to-date.